Methods, Systems and Devices for Administration of Chlorine Dioxide

ABSTRACT

Devices, compositions, systems and methods for the non-cytotoxic delivery of chlorine dioxide to a tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit pursuant to 35 U.S.C. §119(e) of U.S. Provisional Application Nos. 61/135,011, filed on Jul. 15, 2008; 61/106,026, filed Oct. 16, 2008; 61/150,685, filed Feb. 6, 2009; and 61/187,198, filed Jun. 15, 2009, each of which is hereby incorporated by reference in its entirety herein.

BACKGROUND

Chlorine dioxide (ClO₂) is a neutral compound of chlorine in the +IV oxidation state. It disinfects by oxidation; however, it does not chlorinate. It is a relatively small, volatile, and highly energetic molecule, and a free radical even in dilute aqueous solutions. Chlorine dioxide functions as a highly selective oxidant due to its unique, one-electron transfer mechanism in which it is reduced to chlorite (ClO₂″). The pKa for the chlorite ion/chlorous acid equilibrium, is extremely low (pH 1.8). This is remarkably different from the hypochlorous acid/hypochlorite base ion pair equilibrium found near neutrality, and indicates that the chlorite ion will exist as the dominant species in drinking water.

One of the most important physical properties of chlorine dioxide is its high solubility in water, particularly in chilled water. In contrast to the hydrolysis of chlorine gas in water, chlorine dioxide in water does not hydrolyze to any appreciable extent but remains in solution as a dissolved gas.

The traditional method for preparing chlorine dioxide involves reacting sodium chlorite with gaseous chlorine (Cl₂(g)), hypochlorous acid (HOCl), or hydrochloric acid (HCl). The reactions are:

2NaClO₂+Cl₂(g)→2ClO₂(g)+2NaCl  [1a]

2NaClO₂+HOCl→2ClO₂(g)+NaCl+NaOH  [1b]

5NaClO₂+4HCl→4ClO₂(g)+5NaCl+2H₂O  [1c]

Reactions [1a] and [1b] proceed at much greater rates in acidic medium, so substantially all traditional chlorine dioxide generation chemistry results in an acidic product solution having a pH below 3.5. Also, because the kinetics of chlorine dioxide formation are high order in chlorite anion concentration, chlorine dioxide generation is generally done at high concentration (>1000 ppm), which must be diluted to the use concentration for application.

Chlorine dioxide may also be prepared from chlorate anion by either acidification or a combination of acidification and reduction. Examples of such reactions include:

2NaClO₃+4HCl→2ClO₂+Cl₂+2H₂O+2NaCl  [2a]

2HClO₃+H₂C₂O₄→2ClO₂+2CO₂+2H₂O  [2b]

2NaClO₃+H₂SO₄+SO₂→2ClO₂+2NaHSO₄  [2c]

At ambient conditions, all reactions require strongly acidic conditions; most commonly in the range of 7-9 N. Heating of the reagents to higher temperature and continuous removal of chlorine dioxide from the product solution can reduce the acidity needed to less than 1 N.

A method of preparing chlorine dioxide in situ uses a solution referred to as “stabilized chlorine dioxide.” Stabilized chlorine dioxide solutions contain little or no chlorine dioxide, but rather, consist substantially of sodium chlorite at neutral or slightly alkaline pH. Addition of an acid to the sodium chlorite solution activates the sodium chlorite, and chlorine dioxide is generated in situ in the solution. The resulting solution is acidic. Typically, the extent of sodium chlorite conversion to chlorine dioxide is low and a substantial quantity of sodium chlorite remains in the solution.

WO 2007/079287 sets forth in part that the contamination of chlorine dioxide solutions with alkali metal salts accelerates decomposition of aqueous chlorine dioxide solutions. It also discloses a method of preparing a storage-stable aqueous chlorine dioxide solution, wherein the solutiona contains about 2500 ppm or less of alkali metal salt impurities. Alkali metal salt impurities disclosed are sodium chloride, magesium chloride, calcium chloride and sodium sulfate.

Chlorine dioxide is known to be a disinfectant, as well as a strong oxidizing agent. The bactericidal, algaecidal, fungicidal, bleaching, and deodorizing properties of chlorine dioxide are also well known. Therapeutic and cosmetic applications for chlorine dioxide are known.

For example, U.S. Pat. No. 6,287,551 describes the use of stabilized chlorine dioxide solutions for the treatment of Herpes virus infection. U.S. Pat. No. 5,281,412 describes chlorite and chlorine dioxide compositions that provide antiplaque and antigingivitis benefits without staining the teeth.

U.S. Pat. No. 6,479,037 discloses preparing a chlorine dioxide composition for tooth whitening wherein the composition is prepared by combining a chlorine dioxide precursor (CDP) portion with an acidulant (ACD) portion. The CDP portion is a solution of metal chlorite at a pH greater than 7. The ACD is acidic, preferably having a pH of 3.0 to 4.5. The CDP is applied to the tooth surface. The ACD is then applied over the CDP to activate the metal chlorite and produce chlorine dioxide. The pH at the contact interface is preferably less than 6 and, most preferably, in the range of about 3.0 to 4.5. Thus, the resulting chlorine dioxide composition on the tooth surface is acidic. Additionally, this method exposes the oral mucosa to possible contact with a highly acidic reagent (ACD).

However, the current literature summarized above describes the use of chlorine dioxide compositions and methods that are damaging to biological tissues, including soft tissues and hard tissues, such as tooth enamel and dentin. What is needed are systems and methods for using chlorine dioxide in which biological tissue is not damaged.

SUMMARY

The following embodiments meet and address these needs. The following summary is not an extensive overview of the embodiment. It is intended to neither identify key or critical elements of the various embodiments nor delineate the scope of them.

Provided is a method for delivering a substantially oxy-chlorine anion free chlorine dioxide composition to a tissue. The method comprises providing a chlorine dioxide source that includes chlorine dioxide or chlorine dioxide-generating components, and oxy-chlorine anions; providing an oxy-chlorine anion barrier that substantially prohibits passage therethrough of the oxy-chlorine anions and permits passage therethrough of the substantially oxy-chlorine anion free chlorine dioxide composition; and applying the chlorine dioxide source to the tissue with the oxy-chlorine anion barrier interposed between the chlorine dioxide source and the tissue, thereby enabling delivery of the substantially oxy-chlorine anion free chlorine dioxide composition to the tissue.

In some embodiments, the chlorine dioxide source is a particulate precursor of chlorine dioxide. In an embodiment, the substantially oxy-chlorine anion free chlorine dioxide composition comprises less than about 400 milligrams per square meter (mg/m²) oxy-chlorine anions. In an embodiment, the substantially oxy-chlorine anion free chlorine dioxide composition comprises at least about 2.5 mg/m² chlorine dioxide.

In some embodiments, the oxy-chlorine anion barrier comprises a layer interposed between the chlorine dioxide source and the tissue. The layer can be a film selected from the group consisting of polyurethane, polypropylene, polytetrafluoroethylene, polyvinylidene difluoride, polyvinylidene dichloride, combination of polydimethylsiloxane and polytetrafluoroethylene, polystyrene, cellulose acetate, polysiloxane and combinations thereof. In other embodiments, the oxy-chlorine anion barrier comprises a matrix in which the chlorine dioxide source is dispersed.

In some embodiments, the tissue is soft tissue. The tissue can be skin, mucosa, wound tissue or hard tooth tissue. In some embodiments, the wound tissue is a chronic wound. The chronic wound can be a venous ulcer, a diabetic ulcer, or a pressure ulcer.

BRIEF DESCRIPTION OF THE FIGURES

There are depicted in the drawings certain embodiments. However, the compositions, methods, systems, and devices are not limited to the precise arrangements and instrumentalities of the embodiments depicted in the drawings.

FIGS. 1A and 1B are schematic drawings of various embodiments of a composition described herein.

FIGS. 2A-2C are schematic drawings of various embodiments of a device described herein.

FIGS. 3A and 3B are schematic drawings of various embodiments of a device described herein.

DETAILED DESCRIPTION

The following description sets forth in detail certain illustrative aspects and implementations of the embodiments. These are indicative, however, of but a few of the various ways in which the principles of the various compositions and devices may be employed. Other objects, advantages, and novel features of the compositions, devices, systems and methods will become apparent from the following detailed description.

Chlorine dioxide can be of great utility in a variety of applications in biological systems as a result of its disinfectant, bactericidal, algaecidal, fungicidal, bleaching, and deodorizing properties. However, chlorine dioxide compositions have been determined to be damaging to biological tissues. One aspect arises in part from the inventors' determination that the cytotoxic component in chlorine dioxide compositions is not chlorine dioxide itself. Instead, oxy-chlorine anions present in chlorine dioxide compositions have been determined to be the cytotoxic components. One solution to this problem is to prepare substantially non-cyotoxic and/or non-irritating chlorine dioxide solutions and compositions. Such compositions and methods are described in co-pending U.S. Application No. 61/150,685. Another approach is to design systems, compositions and devices that separate or sequester the cytotoxic components of chlorine dioxide compositions while enabling delivery of the chlorine dioxide itself to biological tissues. Accordingly, various aspects include methods, systems, compositions, and devices for delivering chlorine dioxide to biological tissues while substantially preventing contact of those tissues with cytotoxic oxy-chlorine anions, so as to inhibit or prevent tissue damage and/or tissue irritation due to the cytotoxic components of such compositions.

The methods, systems, compositions, and devices are useful as agents in therapeutic and cosmetic applications, including, but not limited to, tooth whitening agents; oral, mucosal and skin disinfectants; oral, mucosal and skin deodorizing agents; and biocidal or antimicrobial agents.

DEFINITIONS

Unless defined otherwise, all technical and scientific terms used herein generally have the same meaning as commonly understood by one of ordinary skill in the art. Generally, the nomenclature used herein and the laboratory procedures in cytopathicity analysis, microbial analysis, organic and inorganic chemistry, and dental clinical research are those well known and commonly employed in the art.

As used herein, each of the following terms has the meaning associated with it.

The articles “a” and “an” are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element.

It is understood that any and all whole or partial integers between any ranges set forth herein are included herein.

The term “about” will be understood by persons of ordinary skill in the art and will vary to some extent on the context in which it is used. Generally, “about” encompasses a range of values that are approximately plus/minus 10% of a reference value. For instance, “about 25%” encompasses values from approximately 22.5% to approximately 27.5%.

As used herein, “biocidal” refers to the property of inactivating or killing pathogens, such as bacteria, algae, viruses, and fungi (e.g., anti-bacterial, anti-algal, antiviral and antifungal).

The term “chlorine dioxide-generating components” refers to at least an oxy-chlorine anion source and an activator of chlorine dioxide generation. In some embodiments, the activator is an acid source. In these embodiments, the components optionally further includes a free halogen source. The free halogen source may be a cationic halogen source, such as chlorine. In other embodiments, the activator is an energy-activatable catalyst. In yet other embodiments, the activator is a dry or anhydrous polar material.

The term “polar material” as used herein, refers to a material which has, as a result of its molecular structure, an electrical dipole moment on a molecular scale. Most commonly, polar materials are organic materials which comprise chemical elements with differing electronegativities. Elements that can induce polarity in organic materials include oxygen, nitrogen, sulfur, halogens, and metals. Polarity may be present in a material to different degrees. A material may be considered more polar if its molecular dipole moment is large, and less polar if its molecular dipole moment is small. For example, ethanol, which supports the electronegativity of the hydroxyl over a short, 2-carbon chain may be considered relatively more polar compared to hexanol (C₆H₁₃OH) which supports the same degree of electronegativity over a 6-carbon chain. The dielectric constant of a material is a convenient measure of polarity of a material. A suitable polar material has a dielectric constant, measured at about 18-25° C., of greater than 2.5. The term “polar material” excludes water and aqueous materials. A polar material may be a solid, a liquid, or a gas.

The term “dry,” as used herein, means a material which contains very little free water, adsorbed water, or water of crystallization.

The term “anhydrous,” as used herein, means a material that does not contain water, such as free water, adsorbed water or water of crystallization. An anhydrous material is also dry, as defined above. However, a dry material is not necessarily anhydrous, as defined herein.

An “efficacious amount” of an agent is intended to mean any amount of the agent that will result in a desired biocidal effect, a desired cosmetic effect, and/or a desired therapeutic biological effect. For, an efficacious amount of an agent used for tooth whitening is an amount that will result in whitening of a tooth with one or more treatments.

By “performance efficacy” is meant the performance of a composition comprising an oxidizing agent in a particular test intended to duplicate or simulate in-use performance. For example, an in vitro study of bacterial kill may be used to simulate performance of a composition intended for use as a hard surface disinfectant. Similarly, an in vitro study of the degree of bleaching of extracted human teeth may be used to simulate tooth whitening performance of a composition intended for tooth whitening.

By “cytotoxic” is meant the property of causing lethal or sublethal damage to mammalian cell structure or function. A composition is deemed “substantially non-cytotoxic” or “not substantially cytotoxic” if the composition meets the United States Pharmacopeia (USP) biological reactivity limits of the Agar Diffusion Test of USP <87> “Biological Reactivity, in vitro,” (approved protocol current in 2007) when the active pharmaceutical ingredient (API) is present in an efficacious amount.

As used herein, “irritating” refers to the property of causing a local inflammatory response, such as reddening, swelling, itching, burning, or blistering, by immediate, prolonged, or repeated contact. For example, inflammation of the gingival tissue in a mammal is an indication of irritation to that tissue. A composition is deemed “substantially non-irritating” or “not substantially irritating,” if the composition is judged to be slightly or not irritating using any standard method for assessing dermal or mucosal irritation. Non-limiting examples of methods useful for assessing dermal irritation include the use of in vitro tests using tissue-engineered dermal tissue, such as EpiDerm™ (MatTek Corp., Ashland, Mass.), which is a human skin tissue model (see, for instance, Chatterjee et al., 2006, Toxicol Letters 167: 85-94) or ex vivo dermis samples. Non-limiting examples of methods useful for mucosal irritation include: HET-CAM (hen's egg test-chorioallantoic membrane); slug mucosal irritation test; and in vitro tests using tissue-engineered oral mucosa or vaginal-ectocervical tissues. Other useful method of irritation measurement include in vivo methods, such as dermal irritation of rat or rabbit skin (e.g., the Draize skin test (OECD, 2002, Test Guidelines 404, Acute Dermal Irritation/Corrosion) and EPA Health Effects Testing Guidelines; OPPTS 870.2500 Acute Dermal Irritation). The skilled artisan is familiar with art-recognized methods of assessing dermal or mucosal irritation.

By “oxy-chlorine anion” is meant chlorite (ClO₂) and/or chlorate (ClO₃) anions.

By “substantially oxy-chlorine anion free chlorine dioxide composition” is meant a composition that contains an efficacious amount of chlorine dioxide and a non-cytotoxic and/or non-irritating concentration of oxychlorine anion, all as defined hereinabove. The composition may contain other components or may consist essentially of oxy-chlorine anion free chlorine dioxide. The composition may be a gas or vapor comprising or consisting essentially of chlorine dioxide, but may be any type of fluid, including a solution or a thickened fluid. The composition may be an aqueous fluid or a non-aqueous fluid.

By “stable” is meant that the components used to form chlorine dioxide, i.e., the chlorine dioxide forming ingredients, are not immediately reactive with each other to form chlorine dioxide. It will be understood that the components may be combined in any fashion, such as sequentially and/or simultaneously, so long as the combination is stable until such time that ClO₂ is to be generated.

By “non-reactive” is meant that a component or ingredient as used is not immediately reactive to an unacceptable degree with other components or ingredients present to form chlorine dioxide or mitigate the ability of any component or ingredient to perform its function in the formulation at the necessary time. As the skilled artisan will recognize, the acceptable timeframe for non-reactivity will depend upon a number of factors, including how the formulation is to be formulated and stored, how long it is to be stored, and how the formulation is to be used. Accordingly, “not immediately reactive” will range from one or more minutes, to one or more hours, to one or more weeks.

The phrase “thickened fluid composition” encompasses compositions which can flow under applied shear stress and which have an apparent viscosity when flowing that is greater than the viscosity of the corresponding aqueous chlorine dioxide solution of the same concentration. This encompasses the full spectrum of thickened fluid compositions, including: fluids that exhibit Newtonian flow (where the ratio of shear rate to shear stress is constant and independent of shear stress), thixotropic fluids (which require a minimum yield stress to be overcome prior to flow, and which also exhibit shear thinning with sustained shear), pseudoplastic and plastic fluids (which require a minimum yield stress to be overcome prior to flow), dilatant fluid compositions (which increase in apparent viscosity with increasing shear rate) and other materials which can flow under applied yield stress.

A “thickener component” refers to a component that has the property of thickening a solution or mixture to which it is added. A “thickener component” is used to make a “thickened fluid composition” as described herein and above.

By “apparent viscosity” is meant the ratio of shear stress to shear rate at any set of shear conditions which result in flow. Apparent viscosity is independent of shear stress for Newtonian fluids and varies with shear rate for non-Newtonian fluid compositions.

The term “hydrophobic” or “water-insoluble,” as used with respect to organic polymers refers to an organic polymer, which has a water solubility of less than about one gram per 100 grams of water at 25° C.

By “acid source” is meant a material, usually a particulate solid material, which is itself acidic or produces an acidic environment when in contact with liquid water or solid oxy-chlorine anion.

The term “particulate” is defined to mean all solid materials. By way of a non-limiting example, particulates may be interspersed with each other to contact one another in some way. These solid materials include particles comprising big particles, small particles or a combination of both big and small particles.

By “source of free halogen” and “free halogen source” is meant a compound or mixtures of compounds which release halogen upon reaction with water.

By “free halogen” is meant halogen as released by a free halogen source.

By “particulate precursor of chlorine dioxide” is meant a mixture of chlorine-dioxide-forming reactants that are particulate. Granules of ASEPTROL (BASF, Florham Park, N.J.) are an exemplary particulate precursor of chlorine dioxide.

By “solid body” is meant a solid shape, preferably a porous solid shape, or a tablet comprising a mixture of granular particulate ingredients wherein the size of the particulate ingredients is substantially smaller than the size of the solid body; by “substantially smaller” is meant at least 50% of the particles have a particle size at least one order of magnitude, and preferably at least two orders of magnitude, smaller than the size of solid body.

By “oxidizing agent” is meant any material that attracts electrons, thereby oxidizing another atom or molecule and thereby undergoing reduction. Exemplary oxidizing agents include chlorine dioxide and peroxides, such as hydrogen peroxide.

A “matrix,” as used herein, is a material that functions as a protective carrier of chlorine dioxide-generating components. A matrix is typically a continuous solid or fluid phase in the materials that can participate in a reaction to form chlorine dioxide are suspended or otherwise contained. The matrix can provide physical shape for the material. If sufficiently hydrophobic, a matrix may protect the materials within from contact with moisture. If sufficiently rigid, a matrix may be formed into a structural member. If sufficiently fluid, a matrix may function as a vehicle to transport the material within the matrix. If sufficiently adhesive, the matrix can provide a means to adhere the material to an inclined or vertical, or horizontal downward surface. A fluid matrix may be a liquid such that it flows immediately upon application of a shear stress, or it may require that a yield stress threshold be exceeded to cause flow. In some embodiments, the matrix is either a fluid, or capable of becoming fluid (e.g., upon heating) such that other components may be combined with and into the matrix (e.g., to initiate reaction to form chlorine dioxide). In other embodiments, the matrix is a continuous solid; chlorine dioxide generation can be initiated by, for instance, penetration of water or water vapor, or by light activation of an energy-activatable catalyst.

By “film” is meant a layer of a material having two dimensions substantially larger than the third dimension. A film may be a liquid or a solid material. For some materials, a liquid film can be converted into a solid film by curing, for instance, by evaporation, heating, drying and/or cross-linking.

Unless otherwise indicated or evident from context, preferences indicated above and herein apply to the entirety of the embodiments discussed herein.

DESCRIPTION

Cytotoxicity of chlorine dioxide-containing compositions results predominantly from the presence of oxy-chlorine anions, and not from the presence of chlorine, which can be a product of chlorine dioxide decomposition. Accordingly, by substantially preventing or inhibiting oxy-chlorine anions present in a chlorine-dioxide containing composition from contacting cells and tissues, including hard tooth tissues, soft tissues, wound tissues, or other target tissues that are targeted for treatment, tissue damage can be measurably reduced or minimized.

Thus, one aspect provides a method for delivering a composition comprising chlorine dioxide and oxy-chlorine anions in a way that the chlorine dioxide reaches the target tissue in an efficacious amount, but the oxy-chlorine anions are substantially inhibited from irritating target tissue or peripheral tissue not targeted for treatment. The method comprises providing a chlorine dioxide source that includes either chlorine dioxide itself or chlorine dioxide-generating components, and further includes the oxy-chlorine anions that cause cytotoxicity to tissues; and further providing an oxy-chlorine anion barrier that substantially prohibits passage therethrough of the oxy-chlorine anions and permits passage therethrough of chlorine dioxide. The chlorine dioxide source is applied to the tissue with the oxy-chlorine anion barrier interposed between the chlorine dioxide source and the tissue, thus preventing or substantially minimizing the oxy-chlorine anion from reaching the tissue, thereby enabling delivery of a substantially oxy-chlorine anion free chlorine dioxide composition to the tissue.

The chlorine dioxide source may comprise any chlorine dioxide-containing composition or ingredients capable of forming chlorine dioxide in situ. Though an already substantially oxy-chlorine anion free chlorine dioxide source (such as that described in co-pending U.S. Application No. 61/150,685) may be utilized, it is assumed that the present method is more applicable to chlorine dioxide sources that contain or produce upon storage or use cytotoxic amounts of oxy-chlorine anions, which need to be prevented from contacting the tissue. The ingredients present in the chlorine dioxide source are preferably compatible with the oxy-chlorine anion barrier during the practice of the method, as well as any pre-use period during which the ingredients are in contact with the barrier. By “compatible” is meant the ingredients do not adversely affect to an unacceptable degree the concentration of chlorine dioxide in the chlorine dioxide source, the inhibition of passage of oxy-chlorine anions, or the permitted passage of chlorine dioxide by the barrier.

The barrier may be in the form of a layer between the chlorine dioxide source and the tissue. In one aspect, the oxy-chlorine barrier, without the chlorine dioxide source, is applied to the tissue first. The chlorine dioxide source is then applied to the barrier layer. In other embodiments, the chlorine dioxide source is applied to the barrier first, and the combination is then applied to the tissue, wherein the barrier layer contacts the tissue. In embodiments where the chlorine dioxide source comprises chlorine dioxide-generating components, the generation of chlorine dioxide may be activated before, during, and/or after application of the barrier (with or without the chlorine dioxide source) to the tissue.

In another embodiment, the tissue may be contacted with a chlorine dioxide source containing a substantially non-cytotoxic and substantially non-irritating amount of oxy-chlorine anions while a second chlorine dioxide source may be located on the side of a barrier opposite the tissue such that additional chlorine dioxide from the second source may pass through the barrier to contact the tissue but passage through the barrier of oxy-chlorine anions in the second source is inhibited.

In another embodiment, the chlorine dioxide source may be dispersed in a matrix comprising one or more barrier substances, such that the oxy-chlorine anions are sequestered away from the tissue, while the chlorine dioxide passes through the barrier substance, if necessary, and the matrix to contact the tissue. In this embodiment, the matrix is applied to the tissue directly or to an optional intervening tissue-contacting layer. In one aspect, the matrix itself is the barrier substance. Exemplary matrix materials that may also function as the barrier include waxes such as paraffin wax, polyethylene, petrolatum, polysiloxanes, polyvinyl alcohol, ethylene-vinyl acetate (EVA), polyurethanes, mixtures thereof and the like. In another aspect, the chlorine dioxide source is coated or encapsulated by the barrier substance. Exemplary barrier substances include polyurethane, polypropylene, polytetrafluoroethylene, polyvinylidene difluoride, polyvinylidene dichloride, combination of polydimethylsiloxane and polytetrafluoroethylene, polystyrene, cellulose acetate, polysiloxane, polyethylene oxide, polyacrylates, mineral oil, paraffin wax, polyisobutylene, polybutene and combinations thereof. Exemplary barrier substances also comprise compounds that bind to oxy-chlorine anions with high affinity and that impede or stop anion migration or diffusion such that a substantially oxy-chlorine anion free chlorine dioxide composition is delivered to a tissue. The compound may form an insoluble precipitate with the oxy-chlorine anion, thereby impeding or stopping diffusion. Alternatively, the compound is immobilized on a substance or material, thereby impeding diffusion or migration. The compound may be cationic, such as ammonium, pyridinium, imidazolium, phosphonium and sulfonium and other positively charged compounds that may be part of the matrix. Optionally, the compound can be immobilized on a oxy-chlorine anion barrier material, to the matrix or on the optional backing layer.

Various materials and membranes can be used an oxy-chlorine anion barrier. The barrier can be in any form, and is typically either a fluid or a solid.

In other embodiments, the oxy-chlorine anion barrier is a fluid, such a petrolatum. In this embodiment, the fluid may be applied to the tissue first, or to an intervening tissue-contacting layer, to form the barrier as a layer and then chlorine dioxide source subsequently applied to the fluid barrier layer. The chlorine dioxide source may be applied as a particulate or may be encompassed in a material to form a film.

In some embodiments, the oxy-chlorine anion barrier is a nonporous membrane. The membrane can be any thickness and can be a single layer or plural layers, provided the membrane remains permeable to chlorine dioxide and substantially non-permeable to oxy-chlorine anions. An exemplary nonporous material is a polyurethane membrane. In some embodiments, the polyurethane membrane is from about 30 to about 100 microns, such as from about 38 to about 76 microns thick. Exemplary polyurethane membranes commercially available include CoTran™ 9701 (3M™ Drug Delivery Systems, St. Paul, Minn.) and ELASTOLLAN (BASF Corp., Wyandotte, Mich.). ELASTOLLAN products are polyether-based thermoplastic polyurethane. A specific example of ELASTOLLAN is ELASTOLLAN 1185A10.

In some embodiments, the oxy-chlorine anion barrier is a microporous membrane permeable to chlorine dioxide and substantially non-permeable to oxy-chlorine anions. The microporous membrane can be any thickness and can be a single layer or plural layers, provided the membrane remains permeable to chlorine dioxide and substantially non-permeable to oxy-chlorine anions. In one example, the microporous membrane can comprise thermo-mechanically expanded polytetrafluoroethylene (e.g., Goretex®) or polyvinylidenedifluoride (PVDF). See, for instance, U.S. Pat. No. 4,683,039. The procedure for formation of an expanded polytetrafluoroethylene is described in U.S. Pat. No. 3,953,566. An exemplary polytetrafluoroethylene (PTFE) membrane, interpenetrating polymer network (IPN) of polydimethylsiloxane and PTFE, is described in U.S. Pat. Nos. 4,832,009, 4,945,125, and 5,980,923. A commercially-available product of this type, Silon-IPN (Bio Med Sciences Inc., Allentown, Pa.), is a single layer and is available in thicknesses between 10 to 750 microns. In one embodiment, the microporous membrane is an IPN of silicone and PTFE having a thickness of about 16 microns. In another example, the membrane is microporous polypropylene film. An exemplary microporous polypropylene film is the material commercially-available from CHEMPLEX Industries (Palm City, Fla.), which is a single layer membrane about 25 microns thick, having a porosity of 55% and a pore size of about 0.21 microns×0.05 microns. The microporous membrane material may be provided as a composite with supporting materials to provide the structural strength required for use. In some embodiments, the membrane is hydrophobic, wherein the hydrophobic nature of the membrane prevents both an aqueous reaction medium and an aqueous recipient medium from passing through the membrane, while allowing molecular diffusion of chlorine dioxide. Features to consider for the materials used for such a barrier include: hydrophobicity of the microporous material, pore size, thickness, and chemical stability towards the attack of chlorine dioxide, chlorine, chlorite, chlorate, chloride, acid, and base.

Various other materials and membranes can be used to form the barrier. For example, the barrier can comprise a microperforated polyolefin membrane; a polystyrene film that is substantially permeable to chlorine dioxide and substantially impermeable to ionic components of the composition; a pervaporation membrane formed from a polymeric material having a relatively open polymeric structure; a cellulose acetate film composite; a polysiloxane or polyurethane material; or a wax. Of course, for contact with soft tissues, the microporous barrier should be substantially non-irritating and substantially non-cytotoxic, particularly in the time scale of typical use of the device and composition.

The pore sizes in the barrier may vary widely, depending on the desired flow rate of the chlorine dioxide through the barrier. The pores should not be so small as to prevent chlorine dioxide gas flow therethrough but also should not be so large that liquid flow is permitted. In one embodiment, the pore size is about 0.21 microns×0.05 microns. The quantity and size of the pores of the barrier may vary widely, depending upon the temperature of the application, the hydrophobicity of the barrier material, the thickness of the barrier material, and also depending upon the desired flow rate of chlorine dioxide through the barrier. Fewer and smaller pores are needed for a given chlorine dioxide flow rate at higher temperature relative to lower temperature, as the vapor pressure of chlorine dioxide from the chlorine dioxide source is higher at the higher temperature. More and larger pores may be used with a highly hydrophobic barrier material, such as PTFE, compared to a less hydrophobic material, such as polyurethane, since the tendency for an aqueous chlorine dioxide source to flow through pores of a highly hydrophobic barrier is lower than it is through the pores of a less hydrophobic barrier. Considerations of barrier strength also dictate the porosity chosen. Generally, the barrier porosity varies from about 1 to about 98%, from about 25 to about 98%, or from about 50% to about 98%.

Also provided are systems, compositions, and devices useful for practicing the method.

In one aspect, a system is provided for delivering a substantially oxy-chlorine anion free chlorine dioxide to a tissue. A typical system comprises a chlorine dioxide source that includes chlorine dioxide or chlorine dioxide-generating components, and oxy-chlorine anions as a first system component; and an oxy-chlorine anion barrier as a second system component, the barrier to be interposed between the chlorine dioxide source and the tissue, wherein the barrier substantially prohibits passage of the oxy-chlorine anions and permits passage of the substantially oxy-chlorine anion free chlorine dioxide composition, thereby enabling delivery of the substantially oxy-chlorine anion free chlorine dioxide to the tissue.

Compositions and devices are also provided to implement the methods and systems described above. Thus, one aspect features a composition for delivering a substantially oxy-chlorine anion free chlorine dioxide composition to a tissue. As illustrated in FIG. 1A, the composition comprises a matrix 12 that includes a chlorine dioxide source 10 comprising chlorine dioxide or chlorine dioxide-generating components, as well as oxy-chlorine anions, and at least one barrier substance 14 that substantially prohibits passage of the oxy-chlorine anions but permits passage of the chlorine dioxide, thereby enabling delivery of the substantially oxy-chlorine anion free chlorine dioxide to the tissue. In one embodiment, the matrix can be a aqueous matrix, or a hydrophobic or anhydrous matrix such as petrolatum. In some embodiments, the matrix itself is the barrier substance. For instance, the matrix can be nonpolar or weakly polar for inhibiting diffusion of oxy-chlorine anions while permitting diffusion of chlorine dioxide. As illustrated in FIG. 1B, the chlorine dioxide source 10 is dispersed within the matrix 12 wherein the matrix is the barrier substance.

The bulk of the matrix can be the barrier substance, or the matrix can comprise a sufficient amount of the barrier substance to carry out the selective delivery of the chlorine dioxide to the tissue. For instance, the matrix can comprise a polymeric material in which reactants or precursors for the formation of chlorine dioxide are embedded or dispersed, wherein the polymeric material is permeable to chlorine dioxide but substantially impermeable to oxy-chlorine anions. See, e.g., U.S. Pat. No. 7,273,567, which describes a composition comprising reactants or precursors and an energy-activatable catalyst embedded in polyethylene, which are activated to produce chlorine dioxide by exposure to light waves, and more particularly, by exposure to ultraviolet radiation.

In some embodiments, the matrix is an adhesive matrix, such as an adhesive polymer matrix. Polymers useful in such adhesive matrices are substantially permeable to chlorine dioxide and are preferably relatively resistant to oxidation by chlorine dioxide so as to limit possible degradation of the polymer and possible consequential change in adhesion. Adhesive polymers are known in the art. See, e.g., U.S. Pat. No. 7,384,650.

The composition can be applied to the tissue, e.g., by spreading it on or otherwise applying it to the tissue, or by incorporating it into a delivery device, such as described below.

Various devices are envisioned for delivering a composition comprising chlorine dioxide and oxy-chlorine anions to target tissue such that an efficacious amount of chlorine dioxide contacts the target tissue, while the oxy-chlorine anions are substantially inhibited or prevented from contacting the tissue. The substantial inhibition reduces, minimizes or precludes damage or irritation to, the target tissue and any surrounding or peripheral tissues.

The devices are typically directionally oriented to comprise a layer distal to the tissue to be contacted and a layer proximal to the tissue to be contacted. The distal layer is also referred to herein as a backing layer. The devices may further comprise a release liner affixed to the tissue-contacting layer, to be removed prior to applying the device to the tissue. In one embodiment, illustrated in FIG. 2A, the device 18 comprises a layer 20 comprising the chlorine dioxide source and a barrier layer 22. In another embodiment, illustrated in FIG. 2B, the device 24 comprises (1) a backing layer 26, (2) a layer 20 comprising the chlorine dioxide source, and (3) a barrier layer 22. The barrier layer may be adapted to contact the tissue, or another layer may be present between the barrier layer and the tissue. The latter embodiment is illustrated in FIG. 2C, wherein the device 28 comprises (1) a backing layer 26, (2) a layer 20 comprising the chlorine dioxide source, (3) a barrier layer 22 and (4) a tissue-contacting layer 30. The barrier layer 22 or the additional tissue-contacting layer 30 can be adhesive. The optional additional tissue-contacting layer 30 is also substantially permeable to chlorine dioxide. In some embodiments, the barrier layer 22 can be made from a thermo-mechanically expanded polytetrafluoroethylene film. In some embodiments, the chlorine dioxide source in layer 20 is a particulate precursor of chlorine dioxide, such as granules of ASEPTROL.

Generally, the backing layer can be made of any suitable material that is substantially impermeable to chlorine dioxide and other components of the chlorine dioxide source. The backing layer may serve as a protective cover for the matrix layer and may also provide a support function. Exemplary materials for the backing layer include films of high and low density polyethylene, polyvinylidene dichloride (PVDC), polyvinylidene difluoride (PVDF), polypropylene, polyurethane, metal foils and the like.

The optional tissue contacting layer can be any material that is substantially permeable to chlorine dioxide. The optional tissue contacting layer may be an absorbent material. Non-limiting examples for this layer include cotton or other natural fiber or synthetic fiber fabrics or meshes, foams and mats.

In another embodiment, illustrated in FIG. 3A, the device 32 comprises a backing layer 26 and a matrix 12 as described above, in which is dispersed the chlorine dioxide source 10 and which comprises at least one barrier substance 14. The matrix may be adapted for contacting the tissue, or an additional tissue-contacting layer may be present. This embodiment is illustrated in FIG. 3B, depicting device 38 comprising a backing layer 26, a matrix 12 and a tissue-contacting layer 30. Either the matrix or the additional tissue-contacting layer can be adhesive. Typically, the matrix is prepared and then coated onto the backing layer.

Also contemplated is a device for continuously and/or intermittently providing a chlorine dioxide solution containing oxy-chlorine anions to a specific tissue, such as a topical lesion. The device is a modification of the irrigation device described in commonly-assigned U.S. Application No. 61/149,784. The modification is the addition of an oxy-chlorine anion barrier. Specifically, the device contemplated herein comprises a chamber comprising an oxy-chlorine anion barrier, wherein the device has an inlet port for supplying a chlorine dioxide solution into the chamber and an outlet port for removing chlorine dioxide solution and an opening covered by the oxy-chlorine anion barrier. The chamber is designed to form a tight substantially leak-proof seal with the tissue surrounding a wound or topical lesion, wherein the opening is proximal to the wound or topical lesion. The oxy-chlorine anion barrier is interposed between the wound or topical lesion and the chamber opening. The chlorine dioxide solution containing oxy-chlorine anions is introduced into the chamber, and chlorine dioxide passes through the oxy-chlorine anion barrier covering the opening and thereby contacting the wound or topical lesion, while the passage of oxy-chlorine anions through the barrier is limited to substantially non-cytotoxic and/or substantially non-irritating levels. This device, like the others described herein, enables the use of highly concentrated chlorine dioxide solutions (e.g., much greater than about 700 ppm) while minimizing or eliminating the cytotoxicity of oxy-chlorine anion typically found in such solutions.

Any method in the art for preparing chlorine dioxide may be used as the chlorine dioxide source to make chlorine dioxide. For instance, there are a number of methods of preparing chlorine dioxide by reacting chlorite ions in water to produce chlorine dioxide gas dissolved in water. The traditional method for preparing chlorine dioxide involves reacting sodium chlorite with gaseous chlorine (Cl₂(g)), hypochlorous acid (HOCl), or hydrochloric acid (HCl). However, because the kinetics of chlorine dioxide formation are high order in chlorite anion concentration, chlorine dioxide generation is generally done at high concentration (>1000 ppm), the resulting chlorine dioxide containing solution typically must be diluted for the use concentration of a given application. Chlorine dioxide may also be prepared from chlorate anion by either acidification or a combination of acidification and reduction. Chlorine dioxide can also be produced by reacting chlorite ions with organic acid anhydrides.

Chlorine dioxide-generating compositions, which are comprised of materials that will generate chlorine dioxide gas upon contact with water vapor, are known in the art. See, e.g., commonly-assigned U.S. Pat. Nos. 6,077,495; 6,294,108; and 7,220,367. U.S. Pat. No. 6,046,243 discloses composites of chlorite salt dissolved in a hydrophilic material and an acid releasing agent in a hydrophobic material. The composite generates chlorine dioxide upon exposure to moisture. Commonly-assigned U.S. Pat. Publication No. 2006/0024369 discloses a chlorine dioxide-generating composite comprising a chlorine dioxide-generating material integrated into an organic matrix. Chlorine dioxide is generated when the composite is exposed to water vapor or electromagnetic energy. Chlorine dioxide generation from a dry or anhydrous chlorine dioxide-generating composition by activation with a dry polar material is disclosed in commonly-assigned co-pending Application No. 61/153,847. U.S. Pat. No. 7,273,567 describes a method of preparing chlorine dioxide from a composition comprising a source of chlorite anions and an energy-activatable catalyst. Exposure of the composition to the appropriate electromagnetic energy activates the catalyst which in turn catalyzes production of chlorine dioxide gas.

Chlorine dioxide solutions can also be produced from solid mixtures, including powders, granules, and solid compacts such as tablets and briquettes, which are comprised of components that will generate chlorine dioxide gas when contacted with liquid water. See, for instance, commonly-assigned U.S. Pat. Nos. 6,432,322; 6,699,404; and 7,182,883; and U.S. Pat. Publication Nos. 2006/0169949 and 2007/0172412. In preferred embodiments, chlorine dioxide is generated from a composition comprising a particulate precursor of chlorine dioxide. Thus, the chlorine dioxide source comprises or consists essentially of a particulate precursor of chlorine dioxide. The particulate precursor employed can be an ASEPTROL product, such ASEPTROL S-Tab2 and ASEPTROL S-Tab10. ASEPTROL S-Tab2 has the following chemical composition by weight (%): NaClO₂ (7%); NaHSO₄ (12%); sodium dichloroisocyanurate dihydrate (NaDCC) (1%); NaCl (40%); MgCl₂ (40%). Example 4 of U.S. Pat. No. 6,432,322 describes an exemplary manufacture process of S-Tab2 tablets. ASEPTROL S-Tab 10 has the following chemical composition by weight (%): NaClO₂ (26%); NaHSO₄ (26%); NaDCC (7%); NaCl (20%); MgCl₂ (21%). Example 5 of U.S. Pat. No. 6,432,322 describes an exemplary manufacture process of S-Tab10 tablets.

Oxy-chlorine anion sources generally include chlorites and chlorates. The oxy-chlorine anion source may be an alkali metal chlorite salt, an alkaline earth metal chlorite salt, an alkali metal chlorate salt, an alkaline earth metal chlorate salt and combinations of such salts. Metal chlorites are preferred. Preferred metal chlorites are alkali metal chlorites, such as sodium chlorite and potassium chlorite. Alkaline earth metal chlorites can also be employed. Examples of alkaline earth metal chlorites include barium chlorite, calcium chlorite, and magnesium chlorite. An exemplary metal chlorite is sodium chlorite.

For chlorine dioxide generation activated by an acid source, the acid source may include inorganic acid salts, salts comprising the anions of strong acids and cations of weak bases, acids that can liberate protons into solution when contacted with water, organic acids, inorganic acids, and mixtures thereof. In some aspects, the acid source is a particulate solid material which does not react substantially with the metal chlorite during dry storage, however, does react with the metal chlorite to form chlorine dioxide when in the presence of an aqueous medium. The acid source may be water soluble, substantially insoluble in water, or intermediate between the two. Exemplary acid sources are those which produce a pH of below about 7, more preferably below about 5.

Exemplary substantially water-soluble, acid-source-forming components include, but are not limited to, water-soluble solid acids such as boric acid, citric acid, tartaric acid, water soluble organic acid anhydrides such as maleic anhydride, and water soluble acid salts such as calcium chloride, magnesium chloride, magnesium nitrate, lithium chloride, magnesium sulfate, aluminum sulfate, sodium acid sulfate (NaHSO₄), sodium dihydrogen phosphate (NaH₂PO₄), potassium acid sulfate (KHSO₄), potassium dihydrogen phosphate (KH₂PO₄), and mixtures thereof. Exemplary acid-source-forming component is sodium acid sulfate (sodium bisulfate). Additional water-soluble, acid-source-forming components will be known to those skilled in the art.

Chlorine dioxide generating components optionally comprise a source of free halogen. In one embodiment, the free halogen source is a free chlorine source, and the free halogen is free chlorine. Suitable examples of free halogen source used in the anhydrous compositions include dichloroisocyanuric acid and salts thereof such as NaDCCA, trichlorocyanuric acid, salts of hypochlorous acid such as sodium, potassium and calcium hypochlorite, bromochlorodimethylhydantoin, dibromodimethylhydantoin and the like. An exemplary source of free halogen is NaDCCA.

For chlorine dioxide generation activated by an energy-activatable catalyst, the energy-activatable catalyst is selected from the group consisting of a metal oxide, a metal sulfide, and a metal phosphide. Exemplary energy-activatable catalysts include metal oxides selected from the group consisting of titanium dioxide (TiO₂); zinc oxide (ZnO); tungsten trioxide (WO₃); ruthenium dioxide (RuO₂); iridium dioxide (IrO₂); tin dioxide (SnO₂); strontium titanate (SrTiO₃); barium titanate (BaTiO₃); tantalum oxide (Ta₂O₅); calcium titanate (CaTiO₃); iron (III) oxide (Fe₂O₃); molybdenum trioxide (MoO₃); niobium pentoxide (NbO₅); indium trioxide (In₂O₃); cadmium oxide (CdO); hafnium oxide (HfO₂); zirconium oxide (ZrO₂); manganese dioxide (MnO₂); copper oxide (Cu₂O); vanadium pentoxide (V₂O₅); chromium trioxide (CrO₃); yttrium trioxide (YO₃); silver oxide (Ag₂O), Ti_(x)Zr_(1-x)O₂ wherein x is between 0 and 1, and combinations thereof. The energy-activatable catalyst can be selected from the group consisting of titanium oxide, zinc oxide, calcium titanate, zirconium oxide and combinations thereof.

Chlorine dioxide-generating components optionally may be present in a matrix. Such matrices may be organic matrices, such as those described in commonly-assigned U.S. Pat. Publication No. 2006/0024369. In these matrices, chlorine dioxide is generated when the composite is exposed to water vapor or electromagnetic energy. The matrix may be a hydrous gel or an anhydrous gel. Hydrophobic matrices may also be employed. Hydrophobic matrix materials include water-impervious solid components such as hydrophobic waxes, water-impervious fluids such as hydrophobic oils, and mixtures of hydrophobic solids and hydrophobic fluids. In embodiments using a hydrophobic matrix, activation of chlorine dioxide may be a dry or anhydrous polar material, as described in co-pending U.S. Application No. 61/153,847.

The amount of chlorine dioxide to be delivered to a tissue (i.e., an efficacious amount) will relate to the result intended from the application of chlorine dioxide to the tissue. The skilled artisan can readily determine the appropriate amount or amount range of chlorine dioxide to be efficacious for a given use. Generally, useful amounts comprise, for example, at least about 5 ppm chlorine dioxide, at least about 20 ppm, and at least about 30 ppm. Typically, the amount of chlorine dioxide can range to about 1000 ppm, up to about 700 ppm, up to about 500 ppm and up to about 200 ppm. In certain embodiments, the chlorine dioxide concentration ranges from about 5 to about 700 ppm, preferably from about 20 to about 500 ppm, and most preferably from about 30 to about 200 ppm chlorine dioxide. In one embodiment, the composition comprises about 30 to about 40 ppm chlorine dioxide. In one embodiment, the composition comprises about 30 ppm. In another embodiment, the composition comprises about 40 ppm. In some embodiments, a useful dose range can be from about 2.5 mg chlorine dioxide per area of contact (in square meters) to about 500 mg/m² chlorine dioxide. Doses of at least about 10 mg/m², at least about 15 mg/m² and at least about 20 mg/m² can also be useful.

The chlorine dioxide that comes into contact with the tissue is substantially oxy-chlorine anion free. In one embodiment, the substantially oxy-chlorine anion free chlorine dioxide that contacts the tissue comprises zero milligram (mg) oxy-chlorine anion per gram to no more than about 0.25 mg oxy-chlorine anion per gram, or from zero to 0.24, 0.23, 0.22, 0.21, or 0.20 mg oxy-chlorine anion per gram composition, or from zero to 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, 0.11, or 0.10 mg oxy-chlorine anion per gram composition, or from zero to 0.09, 0.08, 0.07, 0.06, 0.05 or 0.04 mg oxy-chlorine anion per gram composition, absent other constituents that contribute to cytotoxicity, and is therefore substantially non-cytotoxic. In some embodiments, the substantially oxy-chlorine anion free chlorine dioxide comprises less than about 400 milligrams per square meter of contact area, less than about 375 mg/m², less than about 350 mg/m², than about 325 mg/m², or than about 300 mg/m² oxy-chlorine anions, In some embodiments, the substantially oxy-chlorine anion free chlorine dioxide comprises from zero to less than about 200 mg/m² oxy-chlorine anions. In other embodiments, the substantially oxy-chlorine anion free chlorine dioxide comprises from zero to less than about 100 mg/m² oxy-chlorine anions.

Oxy-chlorine anions can be measured in chlorine dioxide solutions or compositions using any method known to those skilled in the art, including ion chromatography following the general procedures of EPA test method 300 (Pfaff, 1993, “Method 300.0 Determination of Inorganic Anions by Ion Chromatography,” Rev. 2.1, US Environmental Protection Agency) or a titration method based on an amperometric method (Amperometric Method II in Eaton et al, ed., “Standard Methods for the Examination of Water and Wastewater” 19^(th) edition, American Public Health Association, Washington D.C., 1995). Alternatively, oxy-chlorine anions may be measured by a titration technique equivalent to the amperometric method, but which uses the oxidation of iodide to iodine and subsequent titration with sodium thiosulfate to a starch endpoint in place of the amperometric titration; this method is referred to herein as “pH 7 buffered titration.” A chlorite analytical standard can be prepared from technical grade solid sodium chlorite, which is generally assumed to comprise about 80% by weight of pure sodium chlorite.

The method can be practiced with any biological tissue or any biological material. As used herein, “biological tissue” refers any living cell or tissue, or a tissue or cell forming part of any living organism. In particular, the term refers to an animal tissue, preferably mammalian tissue, including one or more of: mucosal tissue, epidermal tissue, dermal tissue, and subcutaneous tissue (also called hypodermis tissue). Mucosal tissue includes buccal mucosa, other oral cavity mucosa (e.g., soft palate mucosa, floor of mouth mucosa and mucosa under the tongue), vaginal mucosa and anal mucosa. These mucosal tissues are collectively referred to herein as “soft tissue.” Biological tissue may be intact or may have one or more incisions, lacerations or other tissue-penetrating opening. “Biological material” includes, but is not limited to, tooth enamel, dentin, fingernails, toe nails, hard keratinized tissues and the like, found in animals, e.g, mammals. In some embodiments, the method is practiced on a chronic wound of soft tissue. Typical wound healing occurs in four, overlapping phases: hemostasis; inflammatory; proliferative; and remodeling. A chronic wound is one which does not heal in the orderly set of stages and in a predictable amount of time. Examples of chronic wounds include: venous ulcers, pressure ulcers, ischemic ulcers and diabetic ulcers, e.g., diabetic foot ulcers. It is believed that the devices and methods disclosed herein will be useful in the treatment of chronic wounds due to the biocidal effect of chlorine dioxide. In particular, chlorine dioxide has been shown to be effective against both methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (P. aeruginosa). See commonly-assigned U.S. Application No. 61/150,685. Both MRSA and P. aeruginosa are resistant to antibiotics and pose an especially significant risk in hospital-associated (nosocomial) infections.

The method can be practiced in any application where a chlorine dioxide containing composition is used, and in particular, in applications where contact or possible contact with biological tissue is involved. In general, chlorine dioxide-containing compositions may be advantageously employed in antimicrobial, in deodorization, and in antiviral processes including germicidal and disinfecting formulations. Chlorine dioxide-generating compositions are effective to destroy, disable, or render harmless a wide variety of microorganisms. Such microorganisms include bacteria, fungi, spores, yeasts, molds, mildews, protozoans, and viruses.

Accordingly, the method described herein may be practiced to reduce microbial or viral populations on the skin of humans and animals, on surfaces or objects, in liquids and gases, or in on medical equipment, and so forth. Chlorine dioxide is also useful in reducing odors. Chlorine dioxide-containing compositions may be utilized in cleaning and sanitizing applications relating to the food industry, hospitality industry, medical industry, and so forth.

Chlorine dioxide-containing compositions may be employed in veterinary products for use on mammalian skin including teat dips, lotions or pastes; skin disinfectants and scrubs, mouth treatment products, foot or hoof treatment products such as treatments for hairy hoof wart disease, ear and eye disease treatment products, post- or pre-surgical scrubs, disinfectants, and so forth. Chlorine dioxide-containing compositions can also be used to reduce microbes and odors in animal enclosures, in animal veterinarian clinics, animal surgical areas, and to reduce animal or human pathogenic (or opportunistic) microbes and viruses on animals and animal products such as eggs. Chlorine dioxide-containing compositions may be used for the treatment of various foods and plant species to reduce the microbial populations on such items, treatment of manufacturing or processing sites handling such species. In other embodiments, the method can be used in cosmetic and/or therapeutic applications including wound care, oral care, toenail/fingernail care including toenail/fingernail antifungal care, periodontal disease treatment, caries prevention, tooth whitening, and hair bleaching.

Tissue irritation can result from highly reactive oxygen species, as well as from extremes of pH, both acidic and basic. To minimize soft tissue irritation of the chlorine dioxide source used in the method has a pH of at least 3.0. To minimize possible hard surface erosion, the pH is at least about 4.5, more preferably at least about 5 or greater than about 6. In another aspect, the oxy-chlorine anion barrier also substantially can inhibit the passage therethrough of protons.

EXAMPLES

The compositions, devices and methods are further described in detail by reference to the following experimental examples. These examples are provided for purposes of illustration only, and are not intended to be limiting unless otherwise specified. Thus, the compositions, devices and methods should in no way be construed as being limited to the following examples, but rather, should be construed to encompass any and all variations which become evident as a result of the teaching provided herein.

To test the barrier properties of a variety of polymeric films, the following experiment was performed. In brief, a sodium chlorite gel composition, known to be cytotoxic, was prepared. A sample of the gel was applied to a square of each film. Each film, carrying the cytotoxic gel, was then tested for cytotoxicity in accordance with the method of USP <87>.

An 0.04 wt % sodium chlorite gel (comprising 2.83 wt % sodium carboxymethylcellulose) was prepared as follows. To 291.2999 grams of de-ionized water, 0.2010 grams of sodium chlorite technical grade (80% purity) was added and the water stirred until the sodium chlorite was dissolved. Over 15 minutes, 8.5 grams of sodium carboxymethylcellulose (Na-CMC) was added to the sodium chlorite solution. The solution was stirred vigorously while the Na-CMC was added. The solution was stirred until all of the Na-CMC was dispersed. The resulting gel was allowed to stand overnight at room temperature so that the Na-CMC was completely hydrated. The gel was stirred vigorously prior to use to disperse any remaining lumps and provide a substantially homogenous composition.

The polymeric films tested in the experiment are summarized in Table 1.

TABLE 1 Sample # Film description Product name Source 1 IPN of silicone and SILON-IPN Bio Med polytetrafluoroethylene Sciences (PTFE) 2 Polytetrafluoroethylene n/a Bio Med (PTFE) Sciences 3 Polyurethane (PU) backing CoTran ™ 3M ™ Drug (2 mil; 52 micron) 9701 Delivery Systems 4 Polyurethane 1185A10 BASF (3 mil; 76 micron) 5 Polyurethane LP9286 BASF (1.5 mil; 38 micron)i 6 Polypropylene (PP), gas- Catalog #325 CHEMPLEX permeable microporous Industries, Inc.

The method of USP <87> involves determining the biological reactivity of mammalian cell cultures following contact with a topical gel product using an agar diffusion test. The cells in this test are L929 mammalian (mouse) fibroblast cells cultured in serum-supplemented MEM (minimum essential medium). A cell monolayer of greater than 80% confluence is grown at 37° C. in a humidified incubator for not less than 24 hours and is then overlaid with agar. The agar layer serves as a “cushion” to protect the cells from mechanical damage, while allowing diffusion of leachable chemicals from the test specimen. Materials to be tested are applied to a piece of filter paper, which is then placed on the agar.

Specifically, a paper disk is dipped in sterile saline to saturate the disk. Excess saline is shaken off. The amount of saline absorbed is determined (disk is weighed before and after wetting using an analytic scale). For each film, a 1 cm×1 cm square is placed onto the surface of the wetted disk and is weighed. Any release paper is removed from the surface of the square contacting the wetted disk. For experiments without cytotoxic gel, release paper, if present, on the opposite of the square was left on the square. For experiments where cytotoxic gel was used, a 0.1 cc aliquot of gel is dispensed onto the film square; all release paper where present is removed. The last bit of dispensed gel is wiped from the lip of the syringe onto the surface of the film. The aliquot is kept within the boundaries of the film square but is not spread out over the entire square. For the gel only control, a 0.1 cc aliquot of gel is dispensed onto the wetted disk. The last bit of dispensed gel is wiped from the lip of the syringe onto the surface of the disk; the gel aliquot is entirely on the wetted disk but is not spread out over the disk. The disk is then weighed again to assess the amount of gel on the sample. The disk is then placed on top of the agar overlay. Cultures are evaluated periodically over time for evidence of cytotoxicity and are graded on a scale of 0 (no signs of cytotoxicity) to 4 (severe cytotoxicity), as summarized in Table 2. A sample is deemed to meet the requirements of the test if none of the cell culture exposed to the sample shows greater than mild cytotoxicity (grade 2) after 48 hours of testing. A sample showing grade 3 or 4 reactivity during the 48 hours is deemed cytotoxic.

TABLE 2 Grade Reactivity Description of Reactivity Zone 0 None No detectable zone around or under specimen 1 Slight Some malformed or degenerated cells under specimen 2 Mild Zone limited to area under specimen 3 Moderate Zone extends to 0.5 to 1.0 cm beyond specimen 4 Severe Zone extends greater than 1.0 cm beyond specimen

Cytotoxicity of three polymeric films was tested in the absence of cytotoxic gel to assess their inherent cytotoxicity (Examples 1-3). Four different polymeric films were tested with cytotoxic gels (Examples 5-8). Cytotoxic gel was tested in the absence of a polymeric file as a control (Example 4).

The results are shown in Table 3.

TABLE 3 Example Film Gel Result of USP <87> 1 IPN of silicone and No Pass polytetrafluoroethylene 2 Polyurethane No Pass (1.5 mil; 38 micron)i 3 Polyurethane No Pass (3 mil; 76 micron) 4 none Yes Fail 5 PTFE Yes Pass 6 Polyurethane (PU) backing Yes Pass (2 mil; 52 micron)† 7 Polyurethane Yes Fail (1.5 mil; 38 micron)i 8 Polypropylene (PP), gas- Yes Pass permeable microporous †3M product literature indicates that CoTran ®9701 is not inherently cytotoxic.

As expected, the gel alone (Example 4) is failed USP <87> and is deemed cytotoxic. The results for Examples 1-3 demonstrate that these films are not inherently cytotoxic. The results for Examples 5, 6 and 8 indicate two things: 1) these films are not inherently cytotoxic and 2) these materials prevent a cytotoxic amount of oxy-chlorine anions from contacting the mammalian cells, via the wetted disk, employed in the USP <87> method. Thus, these films are expected to be suitable as oxy-chlorine anion barriers in the devices and methods described herein. Regarding Example 7, it appears that this film may not be useful as an oxy-chlorine anion barrier. The failure may be due to either or both its thinness or the chemistry of the monomers of the polyurethane permitting passage of a cytotoxic amount of oxy-chlorine anions to the wetted disk and thus the mammalian cells. It is noted that the polyurethane film of Example 6, which is thicker and prepared from different monomers, did pass the test.

The disclosures of each and every patent, patent application, and publication cited herein are hereby incorporated herein by reference in their entirety.

While methods, devices, compositions, and systems described have been disclosed with reference to specific embodiments, it is apparent that other embodiments and variations may be devised by others skilled in the art without departing from the true spirit and scope of the methods, devices, compositions, and systems. The appended claims are intended to be construed to include all such embodiments and equivalent variations. 

1. A method for delivering a substantially oxy-chlorine anion free chlorine dioxide composition to a tissue, the method comprising: providing a chlorine dioxide source that includes chlorine dioxide or chlorine dioxide-generating components, and oxy-chlorine anions; providing an oxy-chlorine anion barrier that substantially prohibits passage therethrough of the oxy-chlorine anions and permits passage therethrough of the substantially oxy-chlorine anion free chlorine dioxide composition; and applying the chlorine dioxide source to the tissue with the oxy-chlorine anion barrier interposed between the chlorine dioxide source and the tissue, thereby enabling delivery of the substantially oxy-chlorine anion free chlorine dioxide composition to the tissue.
 2. The method of claim 1, wherein said chlorine dioxide source is a particulate precursor of chlorine dioxide.
 3. The method of claim 1, wherein the substantially oxy-chlorine anion free chlorine dioxide composition comprises less than about 400 milligrams per square meter (mg/m²) oxy-chlorine anions.
 4. The method of claim 3, wherein the substantially oxy-chlorine anion free chlorine dioxide composition comprises at least about 2.5 mg/m² chlorine dioxide.
 5. The method of claim 1, wherein the oxy-chlorine anion barrier comprises a layer interposed between the chlorine dioxide source and the tissue.
 6. The method of claim 5, wherein the layer is a film selected from the group consisting of polyurethane, polypropylene, polytetrafluoroethylene, polyvinylidene difluoride, polyvinylidene dichloride, combination of polydimethylsiloxane and polytetrafluoroethylene, polystyrene, cellulose acetate, polysiloxane and combinations thereof.
 7. The method of claim 1, wherein the oxy-chlorine anion barrier comprises a matrix in which the chlorine dioxide source is dispersed.
 8. The method of claim 1, wherein the tissue is soft tissue.
 9. The method of claim 8, wherein the tissue is skin or mucosa.
 10. The method of claim 9, wherein the tissue is wound tissue.
 11. The method of claim 1, wherein the tissue is hard tooth tissue.
 12. The method of claim 10, wherein the wound tissue is a chronic wound.
 13. The method of claim 12, wherein the chronic wound is selected from the group consisting of a venous ulcer, a diabetic ulcer, and a pressure ulcer. 